1. Field of the Invention
The present invention relates generally to a wireless cellular communication system, and more particularly, to an Orthogonal Frequency Division Multiple Access (OFDMA) wireless communication system, wherein control and data channels for a particular User Equipment (UE) are time-division multiplexed.
2. Description of the Related Art
In 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) Release 8, i.e., a legacy system, a Physical Downlink Control CHannel (PDCCH) is presented in several initial Orthogonal Frequency Division Multiplexing (OFDM) symbols. The number of OFDM symbols used for the PDCCH is indicated in a Physical Control Format Indication CHannel (PCFICH) in a first OFDM symbol. Each PDCCH includes L Control Channel Elements (CCEs), where L=1, 2, 4, or 8, representing different CCE aggregation levels. Each CCE includes 9 Resource Element Group (REG) spreading on the transmission bandwidth.
Upon receiving the PDCCH, the UE blindly attempts decoding the PDCCH on its search space. The search space contains multiple possible CCE starting indexes and CCE aggregation levels. The UE attempts to decode an expected Downlink Control Information (DCI) format based in this assumption. If a Cyclic Redundancy Check (CRC) passes, the UE assumes a DCI format is successfully received. In legacy 3GPP systems, e.g., 3GPP LTE Releases 8-10, the PDCCH is transmitted using transmit diversity when multiple antennas are available, and the UE uses common reference signals inside the PDCCH region for decoding. The common reference signals are cell-specific.